シャドーイング練習: People Are Mad They're Told to Learn - 動画で英語スピーキングを学ぶ

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So I was, you know, surfing on the old Twitters, and I saw this tweet that wrote a practical introduction to SimD using real examples from Ghosty,

and I thought, hey, that's pretty cool.

But here's the thing, is that often my projects, I don't really feel like need SimD anywhere.

In fact, I took a flame graph of the game I'm making, and only 0.83% of the entire time, I'm actually in the update function.

I don't really feel like I have a huge need, you know, to learn the old SIMDs, whatever.

Hey, cool post though.

But then the next day, this got posted.

My SIMD post was on Hacker News

and the general hostility towards understanding how computers work and owning your own outcomes is really depressing.

A large amount of people seem to simply have the attitude that they hope someone else will pay their bills for them.

It can't be that bad, right?

The vast majority of developers have zero need for learning SIMD.

Why mislead them and make them feel like to be a real developer?

You have to know it.

what?

So an article about SIMD is making people feel like, what am I reading?

So obviously at this point, I had to go and actually learn SIMD because, you know, whether you like this or not, I've never actually used SIMD in any sort of practical use case.

I've understood what it was.

I've called functions that have been SIMD themselves.

I have just never personally hand wrote anything to do with it.

So I thought, hey, given the fact that Hacker News hates it, I probably need to give this a shot and learn about it.

So today you're going to A, have to learn about it, but B, we got some hot takes, okay?

So I got to talk about this whole thing.

Because honestly, why are you misleading them, Mitchell?

Also, just in case anyone's wondering, I'm not going to make the joke that everybody thinks I'm going to make involving SimD, okay?

Not going to happen.

And I'd also like to say thank you to the sponsors.

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Links in the description.

So the article's called Everyone Should Know SIMD.

Now, obviously this became the immediate focal point.

The fact that he said everyone should know SIMD, people just got pissed off.

How dare you say everyone? and it's just like, okay, here's a great concept.

And honestly, it would be really good.

The more people know when programming, right?

I don't think anyone should ever argue that everybody should try

and attempt to know as much as possible so they can make the best quality software out there.

And so when someone says, Hey, everybody should know this.

It's like, okay, I mean, maybe I should know this.

But instead, people were genuinely upset about that.

Good article, but I wouldn't start off with a bold sentence such as SIMD can be simple to understand.

And there you go.

That's the second big one.

People hate the fact that he calls it simple.

Just read the article though.

SIMD has a reputation for being complex.

I've met many a good software engineers who dismiss it as something too complex to learn

or a niche optimization meant only for the highest performance software, not useful in everyday programming.

I think that's wrong.

SIMD can be simple to understand.

And there's a lot of versions of that comment.

It was all over Twitter as well.

Like, how could you say that everybody should know something?

Or how could you say it was easy or simple to understand?

It's complex.

And it's funny because by saying it that way, his first line was, in fact, kind of made obvious.

So me, who's never really understood what SIMD was, I figured, you know what?

Why don't I learn what SIMD is?

Why don't I give it a try, come up with a quick problem, and see if I can make something disproportionately faster, and then I can judge.

Is SimD difficult?

Is it some magical beast?

Or really, was that all that bad at all?

All right, so let's go to the white board.

Oh, gosh.

Oh, Dario.

Dario, stop doing that, Dario.

Don't do that.

Okay, here, hold on.

That's the wrong one, wrong one.

So I thought, what could be a good SimD project?

Well, SimD, you want to do some action that you need to do over a long for loop,

but you have to do like the same comparison a bunch or some same operation over and over again.

At least that's what I thought in my head.

So I thought, okay, a good project would probably be, I have these long log files that I want to be able to find the individual logs out.

And I want to be able to go over this whole list.

And you know, you just generally have to keep doing this over and over and over again.

And it doesn't really matter how long this line is.

It just matters that, yes, we just have to do this over and over again up until the, you know, slash end.

And again, I'm not gonna make the joke that everybody thinks I'm gonna make.

So I figured I would just create a program

that would find each one of these new lines and be able to parse out this delicious JSON.

I dropped the actual parsing of JSON, but instead just looked for the new lines

because I wanted to see how much faster could I make the new line looking.

Next, I actually had to learn what SIMD was.

In the most simple sense, effectively, you can operate instead of on a singular value, say X, you operate on a vector, right?

So pretend you have a vector of X, Y, Z, you could operate on all of these at once.

Let's just say you wanted to compare, say, finding a new line.

Well, what I'd have to do is I'd have to load up a vector with three new lines, kind of like my example, and then in one single CPU operation now this is not

a single cpu cycle cpus are like magic to me i have no idea what's going on underneath there

100

but one i'm just going to call it an operation a

101

single operation can compare this vector to this new line

102

and then it can produce out for you a new vector

103

that's going to say hey this is uh the new lines

104

no new line in the first position there was a new

105

line in the second position there there was no new line in the third position.

106

So I can actually take that and go, okay, was there a new line?

107

Oh, there was.

108

That means I need to find out where the new line was within my vector, and then I can return that.

109

And that's because SIMD literally stands for single instruction, multiple data.

110

And you can see that right here.

111

You can see the fact that I have multiple data and I'm doing a single instruction.

112

Are these equal?

113

So I didn't really know how to do that, but I just followed exactly what was inside the blog post.

114

First, I have to create the constants and initialize any vector stuff.

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I have to loop over the input one vector chunk at a time.

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I perform the comparison.

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I reduce it down to something that I can actually use.

118

And then I just handle the remaining bits at the very, very end.

119

That actually feels, well, pretty straightforward.

120

So this is the naive implementation.

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This is how I would have implemented it if I did not use SIMD.

122

I'm gonna go over the entire data starting at some point, and I'm gonna go and just say, hey, are you a new line?

123

And if you are, then this is the spot.

124

Else I say, hey, no new line found, the end.

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This is your very classic index of approach.

126

Then of course, I just created something to look for all the new lines and just go over all of them.

127

I'm sure there's better way of testing the code.

128

This was good enough for me.

129

And when I had run the program, as you can see here, it would take about 1.54 seconds.

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Okay, not that long.

131

And this is the SIMD version.

132

Yes, it is a lot larger.

133

It's a little bit more tedious to do, but when you break it down into the five steps, it's actually pretty simple.

134

Step one, the broadcast part.

135

Broadcast just means I need to create that constant.

136

Remember how I talked about this new line constant?

137

Well, I do it right here.

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I go, okay, I need to create effectively a byte array that's lanes big.

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Lanes in this case is how many bytes can I fit in my SIMD operations?

140

SIMD turns out to be kind of CPU dependent my CPU can do 256 bits of SIMD operations.

141

So I can do effectively 16 of them at a time if they're byte wide, meaning they're eight bits wide.

142

So this is my little array, 16 eight bit items.

143

Then I just simply create 16 new line bytes and whatever value that is, I think it's hex A.

144

Hex A, new line.

145

Okay, I'm a genius.

146

Actual genius of useless information, of course.

147

Number two, instead of iterating, say one byte at a time, I iterate lanes by data time lanes, of course, is how big my Cindy operation is.

148

In this particular case, it's 16.

149

So I'm doing 16 bytes at a time, instead of one byte at a time.

150

From there, I actually just create my little value array, I just slice off 16 bytes from my array and go, okay, you are now a SIMD vector.

151

From there, I just simply see are these equal, I take all my new lines

152

and compare to all my values in like one single operation instead of doing that little tight for loop.

153

It's just lit I'm doing 16 operations at once.

154

It's kind of cool.

155

Extract most significant bits just really checks for any values that has a one in it.

156

Since all my values should equal zero, if there's no new lines, if there is a new lines, one of them will equal a one, it will grab out that most significant bit.

157

And by doing a cardinality check, if it's not zero, if they're not all zeros, then I have at least one one, then I need to go there and find

158

that one once then I have to manually go through my little SIMD vector and I have to go, okay, which one of you are one and then the first one I find, that's where the new line is.

159

If I don't find a new line, I just add lanes to the end of end.

160

So I'm just incrementing it 16 at a time.

161

So at the very end, you have to do this, which is kind of funny.

162

It's called the scalar tail, which makes a lot of sense if you think about it.

163

Let's just say you have seven bytes remaining.

164

Well, you can't create something that's 16 long from seven bytes.

165

Okay, so then instead, I have to just manually walk the remaining seven.

166

And by doing it that way, if I simply just run this, you can see it's like massively faster.

167

And so yes, am I going to be using SIMD anytime soon?

168

Probably not.

169

I have virtually no problems with performance inside the game I'm making.

170

But now I kind of know the shape I need to have.

171

And now I see why I'm gonna want to use structure of arrays versus array of structures,

172

because there is a huge possibility I could have some mega wins and some future performance optimizations.

173

And honestly, it kind of feels cool.

174

I have to say, it does feel kind of neat.

175

So should everybody know about SIMD?

176

Yeah, why not?

177

It took me an hour to go really learn everything and program up an example and debug it a little bit, not that bad.

178

You can do, Chat Shippity can tell you all about what you need to do.

179

It's actually pretty straightforward.

180

You can ask infinity questions.

181

At the end of the day, which one would you rather have?

182

Maybe a little too much knowledge, knowledge that you don't often use or don't need to use, and you just simply kind of disregard it, but you have it kind of floating in the back of your head,

183

like Dykstra's shortest algorithm, just floating in the back of my head, okay?

184

Priority queue.

185

Or would you rather be this guy?

186

The vast majority of developers have zero need for learning SIMD.

187

Why mislead them?

188

At the end of the day, I'd rather work with the person that wants to know more.

189

I'd rather be the person that wants to know more.

190

And if I never use SIMD and knowing this was completely useless throughout my entire life, I'm happy I know it.

191

The name is, did you know that Go 1.6 right here, as you can see right here, new experimental SIMD, ArchSIMD package?

192

Did you know that Go, even Go, it now has SIMD support?

193

Obviously, you know what that means, right?

194

That means we can sim these nuts on your face again.

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このレッスンの語彙とスピーキングのポイント

このB2レベルのスピーキングレッスンは、動画「People Are Mad They're Told to Learn」を教材にしています。繰り返し出てくる語は次のとおりです：Simd, byte, vector, operation。この動画には、シャドーイング用の文が194文、単語が2368語あります。音声の長さは11:30です。話す速さは速く、1分あたり約206語です。音のつながりや弱く発音される音が多くなります。単語の83%は英語の頻出3,000語に含まれます。残りは練習の前に確認しておきましょう。全194文のうち33文が疑問文なので、疑問文のイントネーションや短い受け答えの練習に向いています。

この動画の重要語彙

動画の中で特に難しい単語15語を、発音と意味つきで紹介します。

単語	発音	意味
byte 名詞	/baɪt/	バイト
vector 名詞	/ˈvɛktɚ/	ベクトル
parse 動詞	/pɑɹs/	解析する, パーズする
optimization 名詞	/ˌɑptəmaɪˈzeɪʃən/	最適化
straightforward 形容詞	/ˌstɹeɪtˈfɔː(ɹ)wə(ɹ)d/	率直, まっすぐ
float 動詞	/fləʊt/	浮かぶ, 浮く
instruction 名詞	/ɪnˈstɹʌkʃən/	指示
cardinality 名詞	/kɑɹdɪˈnælɪti/	濃度
increment 名詞	/ˈɪŋkɹɪmn̩t/	増分, 増加分
initialize 動詞	/ɪˈnɪʃəlaɪz/	初期化する
scalar 形容詞	/ˈskeɪ.lə/	スカラー
tedious 形容詞	/ˈtiː.dɪəs/	退屈な
hostility 名詞	/hɑˈstɪlɪti/	敵対, 敵意
chunk 名詞	/t͡ʃʌŋk/	塊
singular 形容詞	/ˈsɪŋ.ɡjə.lɚ/	唯一, 無二

動画に出てくる句動詞

単語	意味
check out 動詞	試験する, 検査する
find out 動詞	見出す, 調べる
log out 動詞	ログアウトする

繰り返し練習したい文

動画に出てくる短く完結した文です。日常会話でそのまま使えます。

I've understood what it was.
How dare you say everyone?
All right, so let's go to the white board.
At least that's what I thought in my head.
Remember how I talked about this new line constant?

この動画の文法

話し手がよく使っている文型を、動画の実際の表現とともに紹介します。

文型	動画での表現
現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している	I've understood · I've called · have chosen
関係詞節 who / which + 節 — 人や物について情報を加える	this, which is · tail, which makes

注意したい発音

話し手はI'm, don't, gonnaなど、短縮形や弱形を50回使っています。聞こえたとおりの短い形で発音しましょう。

「th」の音: algorithm /ˈælɡəɹɪðm̩/, underneath /ˌʌndɚˈniθ/
「sh」と「zh」の音: optimization /ˌɑptəmaɪˈzeɪʃən/, instruction /ɪnˈstɹʌkʃən/, disproportionately /ˈdɪs.pɹəˌpɔɹ.ʃən.ət.li/, initialize /ɪˈnɪʃəlaɪz/, gosh /ɡɑːʃ/
長い単語（アクセントの位置に注意）: developer /dɪˈvɛləpɚ/, optimization /ˌɑptəmaɪˈzeɪʃən/, manually /ˈmænj(u)əliː/, cardinality /kɑɹdɪˈnælɪti/, disproportionately /ˈdɪs.pɹəˌpɔɹ.ʃən.ət.li/

日本語話者が苦手な音：

/r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: cardinality /kɑɹdɪˈnælɪti/, disproportionately /ˈdɪs.pɹəˌpɔɹ.ʃən.ət.li/, algorithm /ˈælɡəɹɪðm̩/
/v/ — /b/ にならないように、上の歯を下唇に当てる: vector /ˈvɛktɚ/, developer /dɪˈvɛləpɚ/, massively /ˈmæs.ɪv.li/, naive /naɪˈiv/, vibe /vaɪb/
/f/ — 「フ」ではなく、上の歯と下唇で出す: straightforward /ˌstɹeɪtˈfɔː(ɹ)wə(ɹ)d/, float /fləʊt/, focal /ˈfoʊ.kl̩/, infinity /ɪnˈfɪnɪti/, surf /sɝf/

この動画での練習方法

まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
自分の声を録音して元の音声と比べます。byte, vector, parseなどの単語に特に注意しましょう。

シャドーイングとは？英語上達に効果的な理由

シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。

シャドーイングのやり方: ステップ別の完全ガイドを読む →

シャドーイング練習: People Are Mad They're Told to Learn - 動画で英語スピーキングを学ぶ

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